Ni plated coatings for automobile exterior components require an aesthetically appealing silver appearance, and enhanced corrosion resistance against various corrosive environments. However, when anti-freeze or other corrosive agents are attached on an automobile exterior component and the automobile is in a thermal cycle between subzero outdoor temperatures and warm temperatures in an air-conditioned garage, dissolution and corrosion take place on the Ni pleated coatings, which makes the appearance less attractive.
To prevent such dissolution and corrosion, various modifications have been made on the composition of plating solutions to increase the potential of the Ni plated coatings. To further enhance corrosion resistance, as disclosed in Patent Document 1, microporous corrosion-dispersing nickel is plated on a bright nickel, and chromium is plated thereon.
Patent Documents 2 and 3 disclose techniques of vibrating and agitating a plating bath for controlling the potential difference between Ni plated layers, which is considered to affect corrosion resistance.